Method of manufacturing whiting.



WILLIAM NELAN, or Anon, orrro.

METHOD OF MANUFACTURING WRITING.

Specification of Letters Patent.

Patented Mar. 1, 19m.

Application filed March 80, 1908. Serial No. 424,1071

To all whom it may concern:

Be it known that I, WILLIAM NELAN, a

.citizen of the United States, residing at Akron, in the county of Summit and State of Ohio, have invented new and useful Imp'plvements in Methods of Manufacturingv iting, of which the following is a specification.

This invention relates to improvements in methods for producing whitin from chalk. Chalk chemically, as is welf known, is a raw form of calcium carbonate '(CaCO and whiting is refined chalk which has usually been roduced in the past by means of what is known as the water process which comprises thoroughly hydrating the chalk by mixing it with water in a tank in which it is kept agitated by revolving wheels. The resulting mixture is drawn from the tank through an opening near the top into settling tanks connected with one another. at; the. top. The whiting carried in suspgnsion is deposited in these various tan and se arated from the water by precipitation. produced by this process is deposited in the tank nearest the mixing tank and the finest grade in the tank farthest from the mixing tank with the intermediate grades of whiting deposited respectively in the intervening tanks between the two extremes. The amount ofg'rlt in the whiting in the first settling tank is practically the same as in the raw chalk but the amount of grit in the remaining tanks decreases proportionately as the. mixture a proaches the last tank. The purpose of the water is to effect this separation. The whiting thus do osited in the various tanks is drawn ofl an dried in order to render it a commercial roduct.

My process consists first in eh drating the raw chalk by heating, as comp etely as possible; without burning the chalk or in other words without reducing the chalk to lime as done-when itis burned in regular lime kilns. It is essential that the chalk during the process. of dehydration should not be heated to a red heat or to a heat which would dissociate it into calcium oxid (C110) and carbon dioxid (00 but aproach this heat as nearly as posslble in order to insure the most perfect results. It is' also possible to dehydrate the chalk by heating e same to a considerably lower degree of heat than that named and still produce a commercial grade of whiting. The degree ofe coarsest grade of whitingheat to which the chalk is subjected to dehydrate the chalk can be between 23 C. and 300 (1., depending upon the character of the chalk and without dissociating the chalk. When dehydrated, the chalk is subjected to grinding, pulverizing and separating devices for' reducing it to the various degrees of fineness depending upon the grade of whiting required.

Better results will be obtained if the chalk be kept both in a dehydrated and heated condition during the process of grinding, pulverization and se aration, as I have discovered that the big er the temperature of the chalk without'burnin the same during sential to the perfect carrying dut of process that the chalk be reduced to whiting while in a dehydrated condition as the reabsorption of moisture renders it unsuitable for conversion to the finer grades of commercial whiting.

The foregoin processis an adaptation or carrying into. e%ect the old established law of physics that solids expand when heated and contract when cooled. The molecules or dparticles comprisin the chalk are dehy rated and expands by heat permitting them to be more easily acted upon by the grindin pulverizing and separating mechanica agencies, thus making it possible to roduce finer grades of whiting than. cou d be produced by the old well known water process. v q

I have discovered that chalk, chemically known as a form of calcium carbonate, may be heated to such a degree as to thoroughly dehydrate the same and the calcium carbonate when thus heated may be ground, pulverized and separated into whiting preferably under the action of heat and still remam calcium carbonate so long as the heat to which the chalk is subjected is not sumcient to dissociate it in calcium oxid and carbon dioxid.

This process difiers from the old, well known water process in the followin spects: My process is dehydration an the heater or dehydrater, 2 a grinder, '3 a pulold process is hydration. The separation of the coarser particles from the fine, in my process is done by grinding, pulverizing and Separating by mechanical agencies preferably under heat and in the old process the separation is done through the agency of water. It is in many respects an improvement over the old method as a much greater proportion of the finest whiting can be produced from the same amount of chalk than can be obtained by the old water process. It is much shorter and quicker than the old; all of these differences combining to greatly I reduce the cost of production and increase the quality of the product.

As showing one form of an apparatus in i which a method for manufacturing whiting in accordance with this invention can be carried out, reference is had to the accompanying drawing which illustrates an appav ratus for such purpose diagrammatically.

Referring to the drawing, 1 denotes a verizer and 4 a separator. The heated material from the heater or dehydrater is dis- 1 charged into the grinder 2 through the medium of the conducting pipe 5, the material from the grinder is discharged into the pulverizer by the conducting pipe 6 and the material from the pulverizer 3 is discharged into the separator 4: by the conducting pipe 7 The heating devices or the dehydrated grinder, pulverizer and separator are indicated by the reference character 8. The heating devices are shown for the purpose i of not reheating the material but to mainj tain it in a state of dehydration during the 5 steps of the method. It is not essential to i use the heating devices for the grinder, pul 1 verizer and separator because in most cases the material is heated to such an extent in the heater or dehydrater that it will be maintained in a state of dehydration as it passes through the grinder, pulverizer and separator. In case however, that the character of the material is such as to cause it to become hydrated when it leaves the heater or dehydrater, or in case the surroundings are such as to cause the material when it leaves the heater or dehydrater to become hydrated, then the supplementary heating devices are employed to prevent the material from entering a hydrated state.

Having thus described myv inyention, what I claim and desire to secure'sby Letters Pat-- ent 1 The method of producing whiting from chalk which consists in subjecting the chalk to a non-dissociating heat-dehydration sufficient to completely eliminate moisture and while in this state successively subjecting it to grinding, pulverizing and separating operations.

2. A method of producing whiting from raw chalk which consists in first subjecting the chalk to a degree of heat just below the WILLIAM NELAN Witnesses:

JAMES M. HYNEMAN, Lo'r'rln NUSBAUM. 

